This invention relates to a roller apparatus for chopping a strand of glass filaments into relatively long fibers.
In the chopping of fibers from a strand of glass filaments according to the prior art, a plurality of cutting blades 3 are fixedly secured to a driven roller 2 at intervals corresponding to the length of the chopped fibers, as generally shown in FIG. 5. The edges 4 of the cutting blades 3 abut against and penetrate into a resilient feed roller 1, whereby the strand is chopped into fibers and the feed roller is simultaneously driven. To implement the rotation of the feed roller at a constant speed, the cutting blades are disposed at an angle .alpha. with the axis of the cutting roller 2, whereby the feed roller is always engaged by at least two cutting blades in a progressive manner and smoother power transmission is obtained.
Recently, a demand has arisen for relatively long chopped fibers. If the cutting length or distance between the adjacent blades 3 is increased beyond about 13 mm, however, the blades intermittently strike against or engage the feed roller 1 which generates impact vibrations. This causes accelerated wear and deterioration of the synthetic resin or rubber feed roller and damages the edges of the cutting blades.
To overcome this difficulty the height of the cutting blades has been reduced, as shown in FIG. 5, and the peripheral surface 6 of the cutting roller drum 5 is brought into driving contact with the feed roller 1 between the cutting blades as the latter penetrate into the feed roller surface 7. When the strand filaments are still soft, however, the cross-sectional area of the fibers is compressively flattened by the contact pressure, and the cut or chopped fibers tend to stick onto the cutting and feed roller surfaces 6, 7.
It has also been attempted to drivingly couple the feed roller 1 directly to the cutting roller 2 through a separate power transmission, but it is very difficult to revolve the two rollers at exactly equal circumferential speeds owing to the slippage between the various drive train components. Furthermore, the feed roller surface 7 is inherently damaged and worn by repeated contact with the cutting blades, and must be periodically remachined or resurfaced, as a result of which its outside diameter changes. After such maintenance or restoration, it is very difficult to reestablish the drive coupling such that the two rollers rotate at equal circumferential speeds.